I-D Action:draft-ietf-idnabis-mappings-00.txt

Pete Resnick presnick at qualcomm.com
Thu May 28 04:13:32 CEST 2009


On 5/27/09 at 7:20 PM +0900, Martin J. Dürst wrote:

>Section 2 is called "Architectural Principles", which sounds good. 
>But I have mostly found some general explanations of how user input 
>works these days, some explanations about the history of IDNA and 
>the differences between IDNA versions, and so on, nothing getting 
>close to anything Architecturally.

So, obviously my attempt at architectural explanation failed (at 
least for you), but let me see if I can clear up the mystery.

>One reading of the document suggests that the "mapping" happens when 
>characters are input, e.g. from the keyboard.

Sure. Part of the mapping definitely happens when characters are 
input: I have yet to meet a keyboard driver that outputs scan codes 
that look like any character set (let alone Unicode) that I know. And 
it certainly all happens before a string of characters is handed off 
to the wire.

>I think it would be a great contribution to text processing and 
>internationalization on the planet if all data input happened to 
>produce data in NFC. However, I unfortunately have serious doubts 
>that this will happen, even if IDNA suggests it stronly (and even if 
>we require it).

I think we agree on that. (Currently, IDNA2003 requires NFKC mapping. 
IDNA2008 will require NFC as far as I can tell.)

>For other kinds of mappings (e.g. mapping to lower-case), it would 
>be complete havoc if it happened at user input. It would be 
>impossible to type UPPER-case characters.

Well, it would not be complete havoc for an application that was 
implementing IDNA to put that lower-case mapping at some point after 
the keyboard and before punycode. In fact, we require it. I 
personally think there's no need in IDNA to do it before displaying 
it on the screen, but that's a decision about the user community. It 
would certainly be a terrible idea for a word processing application 
to put such a mapping after the keyboard but before insertion into a 
storage file for a document.

>Except for a lot of talk about keybords and the like, there is no 
>discussion about where between the keyboard and the punycode 
>conversion the mapping might happen. If some thought has been given 
>to this, it should be included in the document. If not, somebody 
>better start thinking.

Point taken. I'll add some text. (That is, before I start taking away 
some text, re: Debbie and Paul.)

pr
-- 
Pete Resnick <http://www.qualcomm.com/~presnick/>
Qualcomm Incorporated - Direct phone: (858)651-4478, Fax: (858)651-1102


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